Apparatus for stranding wires

ABSTRACT

Apparatus for stranding wires by twisting, comprises a length of flexible tubing through which the wires are fed. One end of the tube is held stationary while the other end is rotated or twisted first in one direction and then the other. Dividers are positioned at spaced intervals along the tube and at or adjacent to the outlet means for twisting the wires are provided. Also provided are means for holding the twisted wires after exiting from the tube.

United States Patent 1191 1 3,910,022 Reed Oct. 7, 1975 [54] APPARATUS FOR STRANDING WIRES 3,704,580 12/1972 Blanchet et a1. 57/34 AT [75] In ento Phillip John Reed Montreal, 3,847,190 11/1974 Forester 57/77.3 X

d cana a Primary Examiner.lohn Petrakes [73] Assignee: Northern Electric Company Limited, Attorney, A t, r Fir sidne T, Jelly Montreal, Canada [22] Filed: July 18, 1974 [57] ABSTRACT [21] Appl. No. 489,587 Apparatus for stranding wires by twisting, comprises a length of flexible tubing through which the wires are fed. One end of the tube is held stationary while the (3 iiiiiiiiiiiiiiiiii M 5764 other end is rotated or twisted first in one direction [58] Field of searchnm 5.7/3, 6, 34 AT 773 7733, and then the other. DlVldel'S are pos tioned at spaced 57/59 140/149 intervals along the tube and at or ad acent to the outlet means for twisting the wires are provided. Also [56] References Cited provided are means for holding the twisted wires after 't' f th t b UNITED STATES PATENTS mg mm 6 u e 3,572,024 3/1971 Lyons 57/34 AT 10 Claims, 3 Drawing Figures U.S. Patent Oct. 7,1975 3,910,022

II n r/ U I APPARATUS FOR STRANDING WIRES This invention relates to the stranding of wires, and cable, and in particular is concerned with the'stranding of wires in which the direction of twist of the wires is periodically reversed.

For various reasons, both for physical and electrical reasons, it is desirable to twist wires together for use in communication and similar systems. For example, twisting of the pairs of wires as used in telephone systems improves the electrical characteristics, such as reducing. crosstalk.

To continually twist wires together in the same direction requires that the spools, or bobbins, of wire feedingthe twisting apparatus must also revolve about the machine axis. This requires heavy construction and limits the speed of operation. By using a periodically reversing twist it has been possible to avoid the rotation of the wire spools about the machine axis, but other complications arise. Thus it is desirable to twist a fairly long length of the wires and accumulators become necessary. Typical methods of such a system are described in published articles: A New Stranding Method for Making Lay-Reversed Telephone Cables, by Masao Sug; I-Iiroyuki Kamamaro; Juko Wada and Fiji Mizoi; Sumitomo Electrical Technical Review, No. 8, October 1966, pps 40-50; and Principles of SZ-Twisting and Stranding of Communications Cables by Dieter Vogelsberg, in WIRE, Coburg Germany, Issue 116, December 1971.

The present invention enables twisting of wires to continue continuously without the need of an accumulator or similar device and without heavy construction. In its broadest aspect the invention comprises feeding wires through a long flexible tubular member. One end of the tubular member is held stationary and the other end is rotated or twisted, first in one direction and then theother, asthe wires pass through the tube. Dividers are positioned along the length of the tubular member. At the outlet from the tubular member, or adjacent to the outlet, positioning means, rotating with the tubular member, act on the wires to twist them. Means for holding the twisted wires after exiting through the outlet prevent the wires untwisting.

The invention will be readily understood by the following description of one embodiment, and modifications thereto in conjunction with the accompanying diagrammatic drawings, in which:

FIG. 1 illustrates thebasic concept of the present invention;

FIG. 2 is a cross-section on the line Il-II of FIG. 1;

and j FIG. 3 illustrates one form of apparatus embodying the invention.

As illustrated in FIG. .1, two wires are fed from sources, not shown, through a flexible tube 11. The

inletend 12 of the tube 11 is held stationary, as represented diagrammatically at 13. At the outlet end 14 of the tube 11 is a button or disk 15 having two holes 16. The wires 10 pass through the holes 16. In this diagram-.

matical representation the button 15 is shown at the 1 given up to four wires of 19 Gauge havebeen twisted.

twenty turns, thenreversed androtated or twisted in the other direction forty turns that is twenty back to zero or neutral statusand a further twenty turns. This process then continues with rotation back and forth for approximately forty turns each way.

The wire is fed continuously through the tube and thus issues from the outlet end 14 through the holes 16.

The wires are first twisted in one direction and then in the other. By holding the wires by some means, effectively at or close to the button 15, tendency for the wires 10 to become untwisted is avoided.

The outlet end of the tube can rotate at speeds up to, for example 3,000 r.p.m., although this is not a maximum. The linear speed of the wires at the outlet end will vary depending upon the degree of twist, or lay, of the wires. Thus, for example, for a 3 inch'lay the speed can be of the order of 750 feet per minute. To ensure that the wires inside the tube III are twisted linearly, pins 17 are inserted. Pins 17 extend across the bore of the tube 11 and one wire passes on one side and the other wire on the other side. This is seen in FIG. 2. Without pins 17, because of the movement of the wires 10 through the tube as the tube is twisted, the wires twist at or near the outlet end 14, and this causes bunching and jamming of the wires.

If more than two wires are to be twisted extra pins are required, angularly displaced. For example for four wires, pins 17 would be inserted both as in FIGS. 1 and 2 and also at right angles to those illustrated so as to maintain the wires in separate quadrants of the tube bore.

The spacing of the pins is relatively important. The spacing of the pins 17 affects the tension in the wires at the output. The spacing is related to the pulling tension and as a typical example a pin is positioned at every half twist. That is, the pins 17 are so spaced that on full twisting of the outlet end of the tube 11, each pin has rotated more than the pin next to it toward the inlet end of the tube. However, this spacing can be varied, spacings from one-fourth twist to full twist have been used and this is not considered to be the limit. As stated the spacing is related to pulling tension and this is readily determined from normal. technical material. A typical reference source is the Underground System Reference Book by the Edison Electric Institute, published in 1957, specifically referring to page 316. The pulling tension is also affected by the tube length -the longer the tube the lower the tension. From available technical information, typified by the above-mentioned reference, it is possible to relate tube length, pulling tension, spacing of pins, and other details and detertwisted and the number of turns in each direction, and

the tube length has some relationship with pulling tension, as described later. In a tube of the dimensions The tube is, in the particular example, of PVC. The

tubing is of high quality -pure polymer with no filling.

Conveniently it isclear to permit easier threading of the wires 10. t i

FIG. 3 illustrates one form of apparatus embodying the invention. Again, FIG. 3 is very diagrammatic, showing the particularly relevant details only. The wires are shown feeding from spools 20. Spools only rotate about their longitudinal axis and do not rotate about the machine axis. The wires pass over pulleys 21, which may or may not be driven, and pass through the tube 11. The inlet end of the tube 11 is shown supported in a housing 22. This can easily be obtained by inserting a metal tube 23 into the end of tube 11, tube 1 1 being clamped onto the tube 23 by a clamp 24. The tube 23 is then supported in the housing being clamped firmly in the housing. This prevents rotation of the inlet end of the tube 11.

The outlet end of the tube 11 is rotated or twisted in alternate directions by means of two clutch mechanisms 25 and 26. Clutches 25 and 26 are mounted on a hollow shaft 27. Each clutch has a stab shaft 28 which is freely supported on the hollow shaft 27 and a belt pulley 29 is attached to each stab shaft 28. In the particular example the clutches are electromagnetically operated, the electrical leads to the clutches indicated at30. Each clutch has a driving portion connected to the metal pulley 29 and a driven portion connected to the hollow shaft 27. The pulleys are driven in opposite directions, either by separate motors or by a single motor which drives both pulleys by a single belt, the belt passing round one pulley in the opposite direction to the other pulley. This is readily provided by using an idler pulley at the correct position. A disc or button 33, corresponding to button 15 of FIG. 1 is positioned at the end of the hollow shaft 27.

The clutches are activated sequentially to drive the hollow shaft in alternate directions. The outlet end of the tube 11 is connected to the hollow shaft 27 by an extension 31 to the hollow shaft 27, over which the tubell fits and is clamped by a clamp 32. It is important that the system used to activate the clutches 25 and 26 be such as to avoid any cumulative errors. With the high speeds of rotation, i.e. up to 3,000 rpm. or more, and with the high speed of throughput of the wires 10, it will be appreciated that even an error of a fraction of a turn, if consistent, would rapidly result in wire damage. Even a sporadic error, if in the same direction, could be unacceptable.

In the present example the clutches are controlled by microswitches 34 and 35 actuated by a finger 36 extending from a nut 37. Nut 37 runs on a threaded portion 38 of the hollow shaft 27. With such a system cumulative errors cannot occur. It is possible that at each reversal of the shaft 27 it may not be rotated the same number of turns each time but such differences are averaged out and are not cumulative. Leads 39 connect fromthe micro-switches 34 and 35 to a switch box (not shown) to which the leads for the clutches 25 and 26 also connect.

The wires 10 are fed through the tube 11 and hollow shaft 27 under tension. Once the wires exit it is necessary to provide some form of holding means to prevent the wires untwisting under tension. This can be done in various ways. One way is to physically lock in the twist and another is to relieve the wires of tension immediately after twisting.

One way of locking in the twist is to heat the wires very rapidly as they exit through the button 33. The insulation is heated for a very short period, for example 10-15 milliseconds and slight fusing occurs between the coating of the wires. The heating and cooling, is so quick that no damage occurs to the conductor, or any detrimental change to the insulating layer.

Another way of physically locking in the twist is to arrange for the twisted wires to be fed directly into a coding extruder. It can be arranged that the exit from the button 33 is very close to the extruder inlet. Alternatively, a short length of flexible tube can be posi tioned between the button 33 and the inlet of the extruder. The wires are contacted by the extruding material, for example PVC, as soon as the wires enter the extruder and are then locked in their twisted state.

The wires can be relieved of the tension by passing over a capstan. The twisted wires pass a number of times round the capstan and the capstan can be overdriven slightly so that tension is applied to the wires passing through the tube but the wires pass from the capstan, for example to a take-up spool, under little or no tension. Alternatively a caterpillar capstan can be used.

Another alternative is to bring several groups of twisted wires together and twisting or forming into a cable. Physical contact between the wires would then permit untwisting even if tension were applied.

While it is possible to use other flexible means such as a spring, to replace the PVC tube as described above, it has been found very effective to use PVC tubes. Also, it is possible that a tube of plastics material could be extruded to include dividers extending across the bore, similar to diphrams, in which case such dividers would avoid the use of pins 17. It has a very long life and is very flexible. The clutches 25 and 26 can be operated to go from full speed in one direction to full speed in the other direction in the line of approximately /2 revolution. This is assisted by the fact that the inertia of the system is very low. The tube 11 is of small diameter, as is also the hollow shaft 27. The main inertia is in the clutches themselves and these do not reverse but speed up and slow down always in the same direction for the particular clutch. The clutch part attached to the hollow shaft 27 can be small and of low inertia.

As stated, the length of the tube 11, and its interior to exterior diameter, can be varied depending upon the number of wires to be twisted and their size.

In the examples described, a disc or button, 15 of FIG. 1 and 33 in FIG. 3, is shown at or adjacent to the outlet end of the tubular member. In the broadest aspect, the minimal requirement is some means for dividing the outlet end of the tubular member, or the extension thereof as in FIG. 3, into a number of sections corresponding to the number of wires being twisted. Thus, for two wires, either a button with two holes can be used, as described above, or a pin or similar member may extend across the tube. For four wires, two pins at right angles will suffice, and for other numbers of wires a suitable division of the outlet aperture is arranged. For a relatively large number of wires, a disk with a plurality of holes is a convenient arrangement.

While the invention has been described in relation to twisting together two or more individual wires, it is also applicable to the twisting together of groups or wires. Thus a number of pairs, or trios for example, can be twisted together.

What is claimed is:

1. Apparatus for stranding wires, comprising:

an elongate flexible tubular member having an inlet end and an outlet end;

means for holding the inlet end of the flexible tubular member stationary;

means for reciprocating the outlet end of the flexible tubular member through a predetermined number of rotations in alternate directions;

a plurality of independent dividers axially spaced along the tubular member and extending diametrically across the bore of the tubular member to define a plurality of paths through said bore from said inlet end to said outlet end;

twisting means for reciprocation in unison with said outlet, said twisting means including a plurality of apertures, an aperture for each of said plurality of paths.

2. Apparatus as claimed in claim 1, said tubular member comprising a length of tube of plastics material.

3. Apparatus as claimed in claim 2, said plurality of independent dividers comprising pins extending across the tube, the pins spaced apart along the length of the tube.

4. Apparatus as claimed in claim 1, said twisting "means comprising a disc having a plurality of holes therethrough, a hole for each path through said tubular member.

5. Apparatus as claimed in claim 1, said means for reciprocating the outlet end comprising:

a hollow shaft, means for rotating the shaft sequentially in opposite directions;

means connecting the outlet end of the tubular member to one end of said shaft.

6. Apparatus as claimed in claim 5, said twisting means mounted on the end of the shaft remote from the tubular member.

7. Apparatus as claimed in claim 5, said means for rotating the hollow shaft in opposite directions comprising first and second drive means, said drive means driven in opposite directions, and clutch means for selectively clutching one or other of said drive means to said shaft.

8. Apparatus as claimed in claim 7, including a first clutch means for clutching said first drive means to said shaft and a second clutch means for clutching said second drive means to said shaft.

9. Apparatus as claimed in claim 8, including means actuated by rotation of said shaft for selective operation of said clutches.

10. Apparatus as claimed in claim 9, said clutches electrically activated, said means actuated by rotation of said shaft comprising electrical switches, a switch for each clutch. 

1. Apparatus for stranding wires, comprising: an elongate flexible tubular member having an inlet end and an outlet end; means for holding the inlet end of the flexible tubular member stationary; means for reciprocating the outlet end of the flexible tubular member through a predetermined number of rotations in alternate directions; a plurality of independent dividers axially spaced along the tubular member and extending diametrically across the bore of the tubular member to define a plurality of paths through said bore from said inlet end to said outlet end; twisting means for reciprocation in unison with said outlet, said twisting means including a plurality of apertures, an aperture for each of said plurality of paths.
 2. Apparatus as claimed in claim 1, said tubular member comprising a length of tube of plastics material.
 3. Apparatus as claimed in claim 2, said plurality of independent dividers comprising pins extending across the tube, the pins spaced apart along the length of the tube.
 4. Apparatus as claimed in claim 1, said twisting means comprising a disc having a plurality of holes therethrougH, a hole for each path through said tubular member.
 5. Apparatus as claimed in claim 1, said means for reciprocating the outlet end comprising: a hollow shaft, means for rotating the shaft sequentially in opposite directions; means connecting the outlet end of the tubular member to one end of said shaft.
 6. Apparatus as claimed in claim 5, said twisting means mounted on the end of the shaft remote from the tubular member.
 7. Apparatus as claimed in claim 5, said means for rotating the hollow shaft in opposite directions comprising first and second drive means, said drive means driven in opposite directions, and clutch means for selectively clutching one or other of said drive means to said shaft.
 8. Apparatus as claimed in claim 7, including a first clutch means for clutching said first drive means to said shaft and a second clutch means for clutching said second drive means to said shaft.
 9. Apparatus as claimed in claim 8, including means actuated by rotation of said shaft for selective operation of said clutches.
 10. Apparatus as claimed in claim 9, said clutches electrically activated, said means actuated by rotation of said shaft comprising electrical switches, a switch for each clutch. 